This invention relates to an automatic filling and packaging system for filling bags with a material. More particularly, the invention relates to an automatic filling and packaging system of the type having a filling apparatus comprising bag receiving means, bag mouth widening means, filling means, deairing means and temporary sealing means, permanent sealing means and carry-out means arranged in the order mentioned at respective positions to which bags are fed intermittently. The invention further relates to means for positioning, at a prescribed location, each bag supplied to the bag receiving means, means for cutting open one of the four sealed side edges of each bag to provide the bag with a mouth prior to filling, and the means for widening the mouth in order to fill the bag.
An automatic filling and packaging system of the type described is widely used to fill bags with various materials in order to package the materials. Conventionally, the system is designed to handle bags having one side edge already unsealed, this unsealed or open edge serving as a mouth. Recently, sterilized bags have come into use which are completely sealed along their entire periphery at the time of manufacture in order to provide a perfectly sterilized condition inside the bag. Immediately prior to filling the bag, one side edge thereof is cut off to provide the bag with a mouth in preparation for the subsequent filling operation. Since the conventional filling and packaging system mentioned above is not capable of handling such sterilized bags sealed at all four sides, the bags are cut open as described above by a separately provided device.
The conventional filling and packaging system has another shortcoming involving the method through which a bag, cut open as mentioned above, is filled with material. Specifically, the bag mouth, which tends to close due to adhesion between the opposing bag sheets, is widened slightly by appropriate means such as suction devices, a pair of widening members are inserted into the bag through the opened mouth, and the widening members are spread apart to open the mouth widely enough for filling. While held in this state, the bag is brought to the filling station where it is filled with material. The interior of the bag is then deaired and the mouth is sealed to end the filling and packaging process. However, since the mouth of the bag must be spread wide enough to allow filling, the widening members are left inserted in the bag while the bag is being filled. Consequently, depending upon the type of material with which the bag is filled, the material attaches itself to the mouth of the bag owing to the presence of the widening members. This not only destroys the sterilized condition but also results in a poor seal and detracts from the external appearance of the bagged item.
Problems are also encountered in the various means constituting the filling apparatus of the automatic filling and packaging system.
The first problem involves a bag supply device for supplying the filling apparatus with individual bags. In order to fill bags in a regular condition at all times, it is necessary that the bag supply device supply the bag receiving means of the system with bags at a prescribed position. To accomplish this, the conventional bag supply device has bag positioning means.
In a known conventional arrangement, the bag positioning means includes e.g. a fixed receiving plate to which a bag is fed and feed rollers for forcibly feeding the bag in one or two directions on the receiving plate to abut the bag against a positioning member provided at one edge of the receiving plate, whereby the bag is positioned. However, since the bag is forcibly fed by the feed rollers, even a slight positional deviation will cause the bag to wrinkle, the bag tends to fed in a skewed attitude if it is in such an attitude at the start of feeding, and the bag is not correctly positioned if it is thrust against the positioning member too strongly. Moreover, since the extent and manifestation of these problems differ depending upon the type and size of the bags, dealing with them is difficult.
Further, as mentioned above, the conventional filling and packaging system does not posssess means for cutting off one edge of a sterilized bag during the filling process in order to unseal the bag. Since the conventional system therefore is not capable of dealing with these sterilized bags, the bag is cut open by a separately installed apparatus. This means that after being cut open, a bag may remain in stock for an extended period of time before being filled, or that the bag may be carried through a poor environment in order to be brought to the filling and packaging system. In either case, bacteria will have an opportunity to attach to the bag, thus rendering meaningless the use of sterilized bags in the first place.
A problem is also encountered in the means for spreading open the mouth of an unsealed bag to permit filling. Specifically, it is known in the art to adopt an arrangement using suction devices as the bag mouth widening means. In the known arrangement, two suction devices are disposed to oppose each other an both sides of the bag mouth, the devices are moved toward each other to attract both surfaces of the bag and are then separated from each to widen the bag mouth. However, if the opposing sheets of the bag defining the bag mouth happen to be stuck together, or, in particular, if the bag is made of a very thin material such as a polyethylene film, opening the mouth can be very difficult.